More and more critical information is being committed to computers, causing storage capacity to increase at a startling rate. The expansion of data storage requirements has fueled a need for better, more cost-effective tape backup solutions that feature high capacity, high performance and exceptional data integrity.
In the past, helical scan tape technology provided an acceptable solution for mid-range and low-end tape backup systems. Growing demands of contemporary data-intensive applications are quickly outpacing helical scan tape drive capabilities. One technology offering capacity, transfer rate and storage capacity gains over helical scan tape drives, is digital longitudinal streaming tape drives.
Longitudinal tape drives run the tape past a plurality of stationary heads at e.g. 100 to 150 inches per second during read/write data transfer operations, and faster during block searching. These drives place data in plural longitudinal tracks in comparison with slanted stripes of helical scan technology. Since the tracks are arranged longitudinally along the tape, additional recording tracks and channels enable parallel read/write data transfer operations, thereby increasing data transfer rates.
A longitudinal linear tape drive head assembly includes a pair of longitudinal channels. Within each channel, a read or verify head is spanned on each side by a write head, so that data may be read immediately after being written in order to verify the integrity of the data transfer operation, irrespective of direction of tape travel relative to the head. Typically the three heads of each channel are arranged in transverse alignment relative to a longitudinal axis of the tape within a head structure in contact with the tape as it streams past in one direction or the other during operation. One example of a prior head structure for use with digital longitudinal magnetic tape is provided by the present inventor's commonly assigned U.S. Pat. No. 5,055,959 entitled: "Tape Head with Low Spacing Loss Produced by Narrow and Wide Wear Regions", by commonly assigned U.S. patent application Ser. No. 08/094,413 filed on Jul. 19, 1993, for "Magnetic Tape Head", and by commonly assigned U.S. patent application Ser. No. 08/305,117, filed on Sep. 13, 1994, for "Magnetic Tape Head with Self-Regulating Wear Regions", the disclosures thereof being incorporated herein by reference thereto.
Conventional digital longitudinal tape head structures have heretofore typically included a number of discrete read/write core elements. Each core element must be located normally at a very precise location within the head structure in order to achieve desired multi-channel high track density recording within each tape and from tape to tape as tapes are exchanged on the tape drive mechanism. One significant drawback with conventional longitudinal tape heads is that the discrete read/write core elements were separately machined and assembled in place in precise alignment For example, the Quantum DLT6000 linear digital tape head structure requires some 48 miniature spacers and 12 individual cores, along with a multiplicity of islands and shields. All of these discrete elements had to be aligned precisely in place prior to various attachment/bonding procedures in assembly of the head structure, leading to high component and assembly costs.
Another prior approach has been to fabricate tape head elements in a row by using thin film techniques to deposit inductive write elements and magnetoresistive read elements. In this approach plural thin film write/read elements are deposited by thin film techniques upon a suitable wafer substrate. Each of the layers forming the elements is deposited under tight positional tolerances with respect to channel or track spacing, thereby eliminating need for subsequent aligning. The wafer is further processed and sliced into bars, with each bar containing a number of prearranged thin film write/read elements. However, the wafer process typically does not make efficient use of the surface area of the wafer and therefore minimizes the number of heads that may be fabricated upon a single wafer in a very capital intensive, expensive manufacturing process. Thus, while the thin film deposition method has eliminated some of the alignment issues during head assembly, its limited production yields and high capital manufacturing costs have restricted the use of this advanced magnetic recording technology to very high priced tape drive systems, such as the IBM 3480/90 streaming tape systems.
Thus, a hitherto unsolved need has remained for a low cost precision multiple head and manufacturing process for digital longitudinal tape recording systems.